River or Channel Flow Meter

A radar flow meter for rivers uses radar technology to measure water flow in open channels like rivers and canals. These meters typically combine a radar level sensor and a radar current meter (or velocimeter) to measure water level and surface velocity, respectively. By combining this data, along with knowledge of the channel’s geometry, the overall flow rate can be calculated. 

How it works:

• Non-contact measurement:

  Radar flow meters utilize radar waves to measure the water level and surface velocity without direct contact with the water.

  Level measurement:

  A radar level sensor emits a microwave signal towards the water surface, and by analyzing the reflected signal, the distance to the water surface (and thus the water level) can be determined. 

  Velocity measurement:

  A radar current meter (or velocimeter) measures the surface velocity of the water using the Doppler effect. The Doppler effect is the change in frequency of a wave (in this case, radar waves) for an observer who is moving relative to the wave source. By analyzing the Doppler shift in the reflected radar signal, the speed of the water surface can be calculated.

  Flow rate calculation:

  The measured water level and surface velocity, along with information about the channel’s geometry (cross-sectional area), are used to calculate the overall flow rate using established flow equations. For irregular river sections, point method and calculus calculations may be used.